main.ts

import "https://deno.land/std@0.153.0/dotenv/load.ts";
import { parseFeed } from "https://deno.land/x/rss@0.5.3/mod.ts";
import * as discordeno from "https://deno.land/x/discordeno@13.0.0-rc45/mod.ts";
import type { Embed } from "https://deno.land/x/discordeno@13.0.0-rc45/transformers/embed.ts";
import { unescape } from "https://deno.land/x/html_escape@v1.1.5/unescape.ts";
import textClipper from "https://deno.land/x/text_clipper@2.1.0/mod.ts";
import { FeedEntry } from "https://deno.land/x/rss@0.5.3/src/types/feed.ts";

const token = Deno.env.get("BOT_TOKEN") ?? "";
const botId = BigInt(Deno.env.get("BOT_ID") ?? "");
const channelId = BigInt(Deno.env.get("CHANNEL_ID") ?? "");

const link = Deno.env.get("RSS_LINK") ?? "";
const lastPublishedFilePath = `lastPublished/${link.replaceAll("/", "_").replaceAll(":", "_")}.json`;
const lastPublishedFile = await Deno.open(lastPublishedFilePath, {
  read: true,
  write: true,
  create: true,
});
lastPublishedFile.close();

const lastPublishedRaw = (await Deno.readTextFile(lastPublishedFilePath)).trim() || "{}"
const lastPublished = new Date((JSON.parse(lastPublishedRaw)).lastPublished) ?? new Date();

const fetchRSS = async (target: string): Promise<FeedEntry[]> => {
  const response = await fetch(target);
  const xml = await response.text();

  try {
    const { entries } = await parseFeed(xml);
    return entries;
  } catch (error) {
    console.error(JSON.stringify({
      errorMessage: error.message,
      xml,
    }));
    Deno.exit(1);
  }
};

console.log(`lastPublishedRaw: ${JSON.stringify(lastPublished)}`);

const entries = await fetchRSS(link);

const [entriesToPublish, newLastPublished]: [FeedEntry[], Date] = entries
  .filter((it) =>
    it.published !== undefined && it.published > lastPublished
  )
  .reduce(
    (
      acc,
      it,
    ) => [acc[0].concat(it), acc[1] > it.published! ? acc[1] : it.published!],
    [new Array<FeedEntry>(), lastPublished],
  );

console.log(`entriesToPublish: ${entriesToPublish}`);

const embeds: Embed[] = entriesToPublish
  .map((it) => ({
    title: it.title?.value,
    description: textClipper(
      unescape(it.description?.value ?? "")
        .replace(/<[^>]*>/g, ""),
      100,
      { html: false, indicator: "..." },
    ),
    url: it.links[0].href,
  }));

if (embeds.length > 0) {
  const bot = discordeno.createBot({
    token,
    botId,
  });
  discordeno.sendMessage(
    bot,
    channelId,
    {
      embeds,
    },
  );
}

console.log(`newLastPublishedRaw: ${JSON.stringify(lastPublished)}`);

const content = JSON.stringify({ lastPublished: newLastPublished });
await Deno.writeTextFile(lastPublishedFilePath, content);